UV Mapping a simple cube only shows 2 sides textured
It sounds to me like a problem with your lighting: texture viewport mode can do some strange things with your lighting. Try adding a sun lamp illuminating the other side, or switching to rendered or material view with the texture applied in the material. I apologize if I am not answering your question appropriately (I am only going off of your text because my browser won't show your picture). Hope this helps :)